Year	Number
1996	1.67040944099426
1998	1.65375971794128
2000	1.63437485694885
2002	1.6342796087265
2003	1.60647308826447
2004	1.70143103599548
2005	1.55332243442535
2006	1.7969878911972
2007	1.75694394111633
2008	1.78588843345642
2009	1.79852485656738
2010	1.77814149856567
2011	1.76449501514435
2012	1.78074657917023
2013	1.74711012840271
2014	1.69916188716888
2015	1.65277743339539
2016	1.66277503967285
2017	1.71752452850342
2018	1.68902397155762
2019	1.6505092382431
2020	1.76180100440979
2021	1.46519196033478
2022	1.48783588409424